In the case of the hydraulic drive of the type in question, which is known from EP 2 448 720 A1, a large cross-section to the tank is abruptly opened, when the pressure limiting seat valve has responded and as soon as also the larger pressure application area of the valve piston has pressure applied thereto. In the case of an at least approximately simultaneous deactivation of the pump (FIGS. 1, 2), a large volume flow abruptly flows through said large cross-section into the tank and the pressure rapidly collapses at the restriction defined by a valve cone portion of the switching seat valve. Following this, the pressure limiting seat valve returns immediately to its shut-off position. At the valve cone of the switching seat valve, a force is created on the opening side, which opens the switching seat valve and connects the working chamber to the tank via a nozzle limiting the return stroke velocity of the piston. If desired, the return stroke of the piston is stopped at a selectable return stroke position via a volume flow pulse by switching on the pump again, and the switching seat valve is closed. Even if the electric drive motor of the pump is switched off as fast as possible, e.g., by a reversal of poles, it will nevertheless be impossible to avoid coasting of the pump, which will cause a volume flow pulse in the pressure line. Although the pressure limiting seat valve, which has already been closed, will no longer respond to said volume flow pulse, the switching seat valve may respond thereto. Due to the interaction between the pressure limiting seat valve, which responds abruptly to open towards the tank, and the switching seat valve, the hydraulic drive has implemented therein a time logic, which is not defined unequivocally and which, under unfavorable operating conditions, may be outwitted by the coasting volume flow, whereby the switching seat valve will be closed unintentionally or not opened and the piston will either not even start its return stroke or discontinue it prematurely. This time logic is not able to unequivocally differentiate between the volume flow pulse occurring when the pump is switched on intentionally, e.g., for stopping the return stroke, and the coasting volume flow pulse.
DE 10 2006 026 552 A1 relates to a similar hydraulic drive.
Another hydraulic drive of interest is that according to EP 0 944 937 A1, in which a single return valve fulfils the functions of limiting the maximum operating pressure and switching to the piston return stroke, said piston executing its return stroke, however, up to an end position determined by the load acting permanently on the piston. The return stroke can here not be stopped at a selectable return stroke position by switching on the pump again.